At least 1 of the parents would have to be natural born.
Through marriage the partner would become a citizen.
Think Obama!
Even though I disagree with the decision because the way they twisted everything to say his mother could pass citizenship to him.
The father passes citizenship but if he is absent the mother can .. after certain requirements which she did not fulfill at the time.
I believe Obama’s mother was too young to pass on her citizenship to Barrack at his birth.